Simple methods for determination of the release limits for drug products

The potency of a batch of drug product needs to meet a release limits at the time of release so that the potency at the end of shelf life remains above the lower registration limit (LRL). This article discusses two methods which determine the release limits such that the chance to fail LRL at the end of shelf life of the product will be controlled under a desirable level. In additional to controlling failure rate, a method which determines the release limits such that the expected total cost due to rejecting a batch at time zero and at the end of shelf life is minimized. All the methods assume a very flexible sampling schedule, and are simple to implement. Each method is illustrated in an example.